Checking about the Panasonic fz35, I came to know about this new feature called extended optical zoom. Panasonic claims that at low resolutions, the wide angle lens can act as a tele lens and give further optical zoom, or at least I understood so.

One thing struck me: At 12mp, the zoom available is 18x, and at 3mp, it can go upto 35.2x. Mathematically, this is about twice, at one fourth resolution. Now, as far as I know, resolution and size as area are related by square root. Meaning, that from 12mp to 3mp, the resolution becomes one fourth, so the area of the image would become half.

So, without the 2x extended zoom, we would be at 18x. If we shoot that image, and crop it on the computer, such that 3mp equivalent resolution is left, we would get the same result as using the extended zoom to 35.2x, right?

This is the way I think, but I am not sure. Please tell me if I am thinking on the right lines. I dont know if focusing and hence the extended zoom results would be better. If I am wrong, I would very much like to know where!

I have never heard of this before..lol..but it sounds suspiciously like what everyone else on this planet calls "digital zoom", which is another way or saying: "If I crop the center 3MP out of the picture and fill the screen with it, the field of view will be like zooming in optically".

NO: The FZ38/35 has two (well documented) options to extend the zoom beyond the 18x. If one is not using the full 12 MP, the camera by default automatically then enables Extra Optical Zoom mode (EZ). Amazingly the camera does not loose image deterioration and it uses the unused pixels to perform this feature. The other option is to enable the Digital Zoom feature, but as this will indeed reduce the resolution, many users deactivate this feature on their cameras.
The Panasonic Extra Optical Zoom feature is available on a number of FZ models. (In the U.S.A. market, the Extra Optical Zoom is called the Extended Optical Zoom).
I think this EZ Zoom (Extended Optical Zoom) technology is unique to Panasonic as they hold the patent on the use of the optical zoom on unused pixels .

As for the testing of the EZ Zoom, a number of owners have done comparison photos of the moon at full EZ Zoom vs Digital Zoom. Simply put there is no comparison and the results (recently posted on "another" forum site) were outstanding.

To make subjects appear even closer [maximum of 35.2X], do not set the picture size to the highest setting for each aspect ratio...

Further explanation continues on page 54 where it says:

When you set the picture size to [3M] (3 million pixels), the 12M (12.1 million pixels) CCD is cropped to the center 3M (3 million pixels) area, allowing a picture with a higher zoom effect.

My highlighting in red. So yes, this is a digital zoom in everything but name and the same effect could be achieved in post-processing by cropping. If additional evidence were needed dropping the pixel count from 12.1 to 3M pixels (at a particular aspect ratio) results in a further crop factor of 2x which accounts for the difference in the two quoted zoom factors (18x vs. 35.2x) almost exactly. It could only considered as an optical zoom if one didn't have to throw away pixels to achieve the result.

And yes, there's the possibility of applying a further digital zoom of 4x. This all seems to be a triumph of spin over plain English but while I dislike that aspect of the camera's quoted specifications there's no doubt it's a market leader with good reason. And for those who don't care to post-process their images the "extended zoom" will prove useful.

Thats why there is no comparison between an EZ Zoom and Digital Zoom,
the EZ Zoom will produce magnification without Deterioration with the only
caveat being the requirement of the user to use less than 12 MP.
EZ Zoom is in no way or form similar to a Digital Zoom which will ALWAYS
reduce the resolution. It's the "CCD area" that is clearly
stated in the manual that is cropped to the center, not the image.
I have used "area" in red as you left that out, even though it is what is defined on Pg 54.

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This is very disingenuous on Panasonic's part. The extended zoom is not available when the full sensor resolution is used. Thus it is only available when operating the sensor at a cropped size - from the article you linked to:

Extended Optical Zooms work when a smaller image size is selected than the largest size available on a digital camera

That's indistinguishable from cropping during post processing and when one reads

There is little if any loss of image quality like when using a digital zoom

that's absolutely misleading. I might as well say my full-frame 5D MkII can be used as an 8.2MP APS-C camera, with a resultant 1.6x increase in optical zoom, because I can always apply a 1.6x crop in Photoshop. True but informationally useless. The pity of it is that people who should know better just ape the Panasonic marketing spin.

Actually, I'll recant a little from my assertion that EZ is "indistinguishable from cropping during post processing". There's one big difference in those two cases as for EZ to work one has already thrown away three-quarters of the pixels if operating the camera at 3MP as opposed to 12MP. Frankly I'd rather shoot at 12MP, everything else (such as burst speed) being equal, and then have the subsequent opportunity to crop and frame during post-processing. But, as I said before, for those who don't post-process EZ may be of use.

Panasonic CLEARLY advertise the FZ38/35 as an 18x Zoom, thus they are not
misleading or trying to deceive anyone in my opinion. In fact the EZ function
is not prominent in their advertising at all.
I can't understand why all the fuss - It's an 18X zoom camera, with some
additional features than can enhance the zoom.... if you so wish. No other
camera manufacturer has this capability that I know of!!!
They should be applauded for pushing technology innovation.

...and no, I don't work for, or sell Panasonic gear, in fact am a long time
owner of numerous Sony digital cameras, an Olympus 35mm camera
and who happens to also own a single Panasonic camera too

and blank out, for example, the "(under 3M)" bit as being rather complicated and possibly unimportant and just see "Extra Optical Zoom... 35.2x". I think the very existence of this thread demonstrates that confusion can be induced and that despite the fact that our forum membership is more knowledgeable than most about what terms such as "(4:3 / 5M)" might mean.

But as I've been at pains to point out, the FZ35 is a fine camera. if anyone is in any doubt then Gordon's verdict should convince. I know we are both in agreement over that and much else.